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Pelican Technical Article:

Brake Lines Replacement

Kerry Jonsson

Time:

1 hour1 hr

Tab:

$100

Talent:

***

Tools:

11mm, 14mm line wrenches

Applicable Models:

Mercedes-Benz R129 (1990-02)

Parts Required:

Brake hose, brake fluid

Hot Tip:

Use drain pan under line to catch brake fluid

Performance Gain:

Improved braking

Complementary Modification:

Replace the calipers at the same time
When you step on your brake pedal you are really pushing on a piston in your brake master cylinder that compresses hydraulic brake fluid. This pressurized fluid flows through the brake hoses to your caliper. The brake fluid then continues to push on the caliper pistons and forces the brake pads against the rotors. Since the suspension has to move up and down to react to road irregularities the brake line needs to flex with it. Manufacturers use metal brake lines on the body of the car and rubber coated nylon or Teflon brake hoses to make the connection between the body and the floating suspension. If your brake hose is leaking you will loose brake fluid and eventually loose brake pressure. Brake hoses can also collapse internally or become restricted. This will result in poor braking performance. They are a relatively inexpensive part and should be replaced when replacing a problem brake caliper. In this tech article we will go over all the steps to replace your brake hoses.

In order to replace your brake hoses you will need to lift and support your vehicle. See our tech article on jacking up your vehicle.
Front Brake Hose:
Front Brake Hose: This picture illustrates the left side front caliper.
Figure 1

Front Brake Hose: This picture illustrates the left side front caliper. Use a 14 mm line wrench to break loose the hose from the caliper.

Front Brake Hose This Picture illustrates the top of the spring perch.
Figure 2

Front Brake Hose: This picture illustrates the top of the spring perch. This is the mount for the other side of the brake hose. Use an 11 mm line wrench to break loose the flare nut fitting.

Front Brake Hose Fully thread out the flare nut fitting (green arrow) from the line.
Figure 3

Front Brake Hose: Fully thread out the flare nut fitting (green arrow) from the line.

Front Brake Hose Pull the brake hose (green arrow) out of its mount on the spring perch behind the strut assembly.
Figure 4

Front Brake Hose: Pull the brake hose (green arrow) out of its mount on the spring perch behind the strut assembly.

Front Brake Hose Spin the brake hose counterclockwise until it threads out of the caliper.
Figure 5

Front Brake Hose: Spin the brake hose counterclockwise until it threads out of the caliper. Installation is the reverse of the removal steps. Thread the line into the caliper first then install the mount on the spring perch. Attach metal flare nut fitting at the spring perch and tighten. Fill the master cylinder with brake fluid and bleed the brakes. See our technical article on brake bleeding.

Rear Brake Hose: 
Rear Brake Hose ThisPicture illustrates the left side rear caliper.
Figure 6

Rear Brake Hose: This picture illustrates the left side rear caliper. With the 14 mm wrench break loose the hose at the caliper.

Rear Brake Hose ThisPicture illustrates behind the left side rear spring perch.
Figure 7

Rear Brake Hose: This picture illustrates behind the left side rear spring perch. Use an 11 mm line wrench to remove the flare nut fitting from the line.

Rear Brake Hose With the flare nut fitting fully loosened pull out the top of the rear brake line.
Figure 8

Rear Brake Hose: With the flare nut fitting fully loosened pull out the top of the rear brake line.

Rear Brake Hose Spin the brake hose counterclockwise until it threads out of the caliper.
Figure 9

Rear Brake Hose: Spin the brake hose counterclockwise until it threads out of the caliper. Installation is the reverse of the removal steps. Thread the line into the caliper first then install the mount on the spring perch. Attach metal flare nut fitting and tighten. Fill the master cylinder with brake fluid and bleed the brakes. See our technical article on brake bleeding.

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Page last updated: Sat 2/25/2017 02:29:03 AM